It’s time to talk about Scooter Gennett

Scooter Gennett, a 27-year professional baseball player, is certainly of the right age to remember the Razor Scooter craze that swept the nation in the year 2000. The aluminum-framed scooter affixed with 98mm polyurethane wheels sold over 5 million units in its first six months of production, enabling little nine-year old demons to zip around basketball courts everywhere and fall over hilariously like this. Whether Gennett owned a Razor Scooter, and whether that influenced his decision to go by ‘Scooter’ instead of his birth-name Ryan, is another story.

But Gennett’s sudden rise to prominence over the last month certainly bears a resemblance to the sudden and unexpected dominance of the Razor Scooter. Gennett, who made his major league debut in 2013 with the Milwaukee Brewers and was claimed off waivers by the Cincinnati Reds in March, smacked 38 home runs in approximately 500 career games prior to June 6th, 2017. That night, in a game against the St. Louis Cardinals, Gennett became the 17th player in MLB history to hit four home runs in a game. Since then Gennett added another eight home runs, bringing his career total to 50, a 31.6% increase over the amount he had when the calendar rolled over to June.

Since June 6th, Gennett is tied for second in the majors in home runs with 12, is second in slugging percentage at .776 and second in isolated slugging percentage at .418. For the 5’10”, 185lbs Gennett, who never hit more than nine home runs at any minor league level and previously profiled as a meek-hitting slap hitter, to be in the company of Aaron Judge, George Springer and Cody Bellinger in a variety of power statistics is damn impressive.

With that said, we’ve all seen one-month power surges from unlikely candidates before. Yankees’ left fielder Shane Spencer hit 10 home runs to go along with an absurd .910 slugging percentage across 73 plate appearances in 1998, but subsequently failed to cement himself as an MLB regular and eventually retired only six years later. Glenalen Hill, a decent but unspectacular journeyman outfielder, hit 16 home runs in 143 plate appearances at the age of 35 for the Yankees in 2000 after being acquired from the Cubs. He retired shortly thereafter.

Gennett has improved across the board offensively from his previous two seasons with the Brewers. His BABIP, average, on-base percentage, home runs, HR/AB ratio, slugging percentage wRC+ are all vastly improved in 2017. In particular, his HR/AB ratio has skyrocketed from a paltry 2.8% to a robust 7.2%, a 2.5x increase. The increased home runs are a large driver of the increased slugging percentage and wRC+. But the BABIP, which was in a respectable range of .309 to .315 with the Brewers, has also gone up quite a bit to .347, which underlies the increased batting average and on-base percentage as well. Thus, the two central questions we need to ask are 1) is Gennett’s increased home run prowess real and sustainable? and 2) is his increased ability to generate hits on balls in play sustainable?

Increased power

Gennett’s diminutive stature and lack of historical power draw skepticism to his recent home run ability. Sure enough, Gennett operated at a pip-squeak home run to fly ball ratio of 6.7% in 2015 and improved that to 10.5% in 2016. However, this season he’s swatting a home run on a robust 25.4% of all his fly balls. That type of HR/FB ratio is normally reserved for the game’s elite power hitters, and sure enough the names dotted around Gennett’s 23rd placement on the 2017 HR/FB list are traditional sluggers like Ryan Braun, Joey Gallo, Scott Schebler and Ryan Zimmerman.

Gennett’s sudden surge in converting fly ball outs to home runs doesn’t pass the sniff test on the surface, but let’s delve deeper into the numbers. First off, Gennett is hitting more fly balls than ever this season, continuing an upward trend from 29.8% in 2015 to 34.5% in 2016 and finally 37.3% in 2017. While 37.3% is not an overly impressive flyball metric, it’s above average and shows that Gennett has changed his approach to swing for the fences a bit more.

Gennett’s four home run swings on June 6th.

Arguably the most important factor in determining whether a flyball is a home run is whether it’s pulled or not. Generally speaking, flyballs to center result in outs in most ballparks due to extended field dimensions compared to the corners of the outfield. Most hitters also have difficulty consistently hitting home runs to the opposite field, so the fact that Gennett increased his flyball pull percentage from 14.4% in 2015 to 30.5% in 2017 is a good sign. For some perspective, Gennett’s 30.5% flyball pull rate ranks 63rd out of 274 qualifying batters this season.

Not only is Gennett hitting more flyballs, and pulling those flyballs more, but he is also hitting those pulled flyballs much harder. His 33.3% flyball hard hit rate in 2015 was fairly average, and he improved on that marginally in 2016 to 36.8%. But Gennett has found a new gear in 2017, laying the wood to flyballs an elite 54.2% of the time, which ranks 13th in the majors. As a corollary to his increased batted ball authority on flyballs, Gennett’s soft hit percentage on flyballs has plummeted from 25.6% to 13.6%.

The last item to consider in Gennett’s batted ball profile is his tendency to hit barrels. For a refresher, barrels are batted balls struck at the ideal exit velocity and launch angle to produce hits, typically extra-base hits. Barrels produce a batting average of over .500 and a slugging percentage of 1.500, so the more barrels the better for a hitter. Sure enough, Gennett’s barrels per batted ball ratio has increased over seven-fold from his 2015 season to 7.5% in 2017.

Putting it all together, Gennett is hitting more flyballs, pulling those flyballs more, hitting those flyballs harder and is hitting a lot more barrels overall. At this point we can safely determine that Gennett’s home run surge is not simply a fluke. Whether pitchers will begin to adjust to his new approach, and whether he can sustain a 25.4% HR/FB rate are different questions. Given Gennett’s batted ball authority improvements, I think it’s reasonable that he sustains a HR/FB rate in the low 20%s. That, combined with his current flyball ratio in the upper 30%s, would make him a consistent 30 home run hitter over a full season.

Increased batting average

Gennett’s 2017 batting average of .311 is a career high, largely built on a BABIP of .347. While Gennett is certainly hitting the ball harder this season, the changes in his swing profile do not suggest that a .347 BABIP is sustainable moving forward.

For starters, hitting more flyballs generally leads to a lower BABIP, not a higher one. The reasons are evidenced by Gennett’s flyball BABIPs going back to 2015. He’s been fairly consistent, landing a hit in the field of play on .155 to .178 of his flyballs hit. Grounders typically produce slightly better BABIP rates, and we can see Gennett has been fairly consistent in his performance on those as well, occupying a range of .238 to .250 since 2017. So, without any real change in BABIP ability on flyballs and groundballs, we should see a reduction in BABIP by trading groundballs for flyballs overall.

Where Gennett has seen a real spike is his BABIP on line drives, up from .650 in 2016 to .833 in 2017. While Gennett is hitting the ball harder this year, landing a hit on 5/6 of all line drives is an absurd number, one that is actually top 10 in baseball in 2017. For some added perspective, over the two years from June 2015 to June 2017, the league median line drive BABIP was around .685. Some of the betters hitters in the league maintain LD BABIP figures above .750, however that probably shouldn’t be the expectation for Gennett moving forward.

One difference in Gennett’s line drives this season is that far more of them are pulled. To be honest I don’t know quite what to make of that. Pulling groundballs hurts BABIP, but if a ball is hit on a rope it might not matter whether it’s hit to the pull or opposite side. Either way, we shouldn’t expect Gennett to maintain a .833 BABIP on line drives.

Using Mike Podhorzer’s xBABIP calculator, Gennett should be running somewhere around a .320 BABIP in 2017 based on his current peripherals. This makes sense, as it’s slightly above his performance in 2015 and 2016, but not overly so because his new power stroke limits the occurrence of hits in the field of play.

If Gennett’s strikeout rates remain in the low 20%s, a BABIP regression to the .320 range would make him a .280 average hitter.

In summary

Much to my surprise, most of Scooter Gennett’s gains in power and batting average are supported by real changes in his approach at the plate. More pulled and hard hit fly balls are leading to more extra base hits, while the added batted ball exit velocity has also nudged up his batting average. If he continues to get regular at bats, it’s reasonable to expect Gennett to be a .280 AVG / 30 HR player moving forward.